1. Field of the Invention
This invention relates to an optical disk device in which an optical disk is loaded to perform either a recording operation or a reproducing operation.
2. Description of the Related Art
In an optical disk device, an optical disk is loaded and a laser beam is incident to an information recording surface of the optical disk to record information at the information recording surface or reproduce the recorded information.
FIG. 6 is a perspective view for showing a prior art optical disk device. The optical disk device 100 is mainly comprised of a substantial rectangular-shaped chassis 101 formed by a sheet metal and having partially a recess at its outer edge; a spindle motor 103 arranged on the chassis 101 and having a turntable 102 coaxially attached thereto; guide shafts 104, 105 arranged in parallel to each other; an optical pickup 106 having an objective lens 106a arranged between.the guide shafts 104, 105 and having a substantial rectangular outer shape; and a feeder mechanism to be described later for use in feeding the optical pickup 106 in a longitudinal direction of the guide shafts 104, 105.
Then, a constitution of the optical disk device 100 will be described in detail as follows.
At first, the central part of the chassis 101 is formed with a substantial rectangular-shaped hole 101a. Then, the spindle motor 103 is attached and fixed to the surface of the chassis 101 at one edge of the chassis 101 in a longitudinal, direction at the hole 101a. In addition, at both sides of the hole 101a in a lateral direction of the chassis 101 are arranged the guide shafts 104, 105 in such a way that they are in parallel to each other in the longitudinal direction and in parallel with the disk installing surface 102a of the turntable 102. One end of the guide shaft 104 at the side of the turntable 102 (hereinafter merely called as one end of the guide shaft 104) is positioned in a longitudinal direction and radial direction by the position setting pieces 101b and 101c formed while a part of the chassis 101 is protruded and bent, and one end of the guide shaft is attached and fixed to the chassis 101 with a screw 107. In addition, the other end of the guide shaft 104 (hereinafter similarly called as the other end of the guide shaft 104) is also similarly positioned by the position setting piece 101d, biased resiliently toward the surface of the chassis 101 by a leaf spring 108 fixed to the chassis 101 with a screw 111 and supported there. In turn, each of both ends of the guide shaft 105 is also similarly positioned by position setting pieces 101e, 101f and 101g, 101h and at the same time resiliently biased toward the surface of the chassis 101 by leaf springs 109, 110 fixed with screws 112, 113 and supported there.
Further, the guide shaft 104 is inserted into round holes. 106e, 106f formed at each of bent pieces 106c, 106d arranged at one end of the optical pickup 106 in its longitudinal direction, and a cutout groove 106h formed at the bent piece 106g arranged at the other end opposite to the round holes 106e, 106f is slidably supported at the guide shaft 105, thereby the optical pickup 106 is movably guided in a longitudinal direction (the radial direction of the optical disk) of the guide shafts, 104, 105 and further guided in such a way that a distance between the optical pickup 106 and the objective lens 106a and a distance between the objective lens 106a of the optical pickup 106 and the surface of the optical disk (not shown) is always kept at an approximate same distance.
Further, an attitude of the optical pickup 106 can be changed by a method wherein, in order to cause an optical axis of the objective lens 106a of the optical pickup 106 is faced to cross at a right angle with the information recording surface of the optical disk, the other end of the guide shaft 104 is moved in a direction H1 substantially crossing at a right angle with the surface of the chassis 101 and each of both ends of the guide shaft 105 is moved in the directions H2, H3 to adjust the guide shafts 104, 105 to be inclined against the surface of the chassis 101. A method for adjusting the guide shafts 104, 105 will be described later.
A nut member 114 is integrally fixed to the optical pickup 106 at one end of the bent pieces 106c, 106d of the pickup 106, and a nut part 114a of the nut member 114 is resiliently biased; and engaged with a valley of thread at a lead screw 115 which is substantially in parallel with the guide shaft 104 and rotatably arranged. In turn, a spur gear 116 is coaxially fixed to an end part of the lead screw 115 opposite to the turntable 102 in such a way that the spur gear is integrally rotated with the lead screw, and a spur gear 117 engaged with the spur gear 116 is fixed to a rotating shaft of a feeder motor 118. Then, this feeder motor 118 is rotationally driven to cause the lead screw 115 to be rotated under a gear ratio determined by the spur gear 116 and the spur gear 117, and then the optical pickup 106 having the nut member 114 fixed thereto is fed in a radial direction of the optical disk.
In addition, the optical disk is installed on the disk mounting surface 102a of the turntable 102, rotated by the spindle motor 103, a laser beam radiated from the objective lens 106a of the optical pickup 106 is condensed at the information recording surface of the optical disk, the return beam reflected from the information recording surface in response to information is received within the optical pickup 106 through the objective lens 106a again, thereby it is possible to read information in the information recording surface of the optical disk or record information onto the information recording surface. Further, the optical pickup, 106 performs a controlled motion in accordance with the information recording surface of the optical disk by the feeder motor 118 along the longitudinal directions of the guide shafts 104, 105.
Referring now to FIG. 7, a method for adjusting an inclination of each of the guide shafts 104, 105 will be described. FIG. 7 shows a sectional view taken along line 7xe2x80x947 of FIG. 6.
As shown in this figure, the chassis 101 is formed with a downward protruded indentation 101i at the position of the other end of the guide shaft 105 biased by the leaf spring 110. Then, an adjustment screw 119 is rotatably arranged below an abutment surface of the leaf spring 110 against the guide shaft 105 and at the central part of the indentation 101i in such a way that it may be protruded from below the chassis 101 in an upward direction. Then, the other end of the guide shaft 105 is mounted on the extremity end surface 119a of the adjustment screw 119 arranged at a predetermined height and a pressing surface 110a of the leaf spring 110 pushes against the surface of the guide shaft 105 in a slant direction under a state in which the right side of the guide shaft 105 as viewed in the figure is abutted against an abutting surface 101hxe2x80x2 of the position setting piece 101h (refer to FIG. 6), thereby the other end of the guide shaft 105 is resiliently biased by the screw extremity end surface 119a and the abutting surface 101hxe2x80x2 and supported there.
With such an arrangement as above, the adjustment screw 119 is rotated to cause the other end of the guide shaft 105 to be moved in a direction H3 as shown in the figure, i.e. if the adjustment screw 119 is rotated in a clockwise direction, the other end of the guide shaft 105 can be adjusted in an upward, direction H3xe2x80x2 and if the adjustment screw 119 is rotated in a counter-clockwise direction, the other end of the guide shaft 105 can be adjusted in a downward direction H3xe2x80x2.
The constitution shown in FIG. 7 is similarly applied in the case that other leaf springs 108, 109 are arranged. It is assumed that each of the adjustment screws arranged at the positions of the leaf springs 108, 109 is denoted by reference numerals 120, 121, respectively. With such an arrangement as above, an attitude of the optical pickup 106 can be changed by a method wherein an inclination of each of the guide shafts 104, 105 is changed by rotating the adjustment screws 119, 120 and 121. For example, referring now to FIG. 6, the adjustment screws 119, 121 (placed at positions of the leaf springs 110, 109, respectively) are rotated in the same direction by the same angle to cause each of both ends of the guide shaft 105 to be moved in the same direction by the same distance in the directions H3xe2x80x2, H2xe2x80x2 (upward direction), or the directions H3xe2x80x3, H2xe2x80x3 (downward direction), resulting in that the cutout groove 106h of the optical pickup 106 engaged with the guide shaft 105 is similarly moved upward or downward by the same distance and accordingly an angle of the optical axis of the objective lens 106a of the optical pickup 106 in respect to a direction crossing at a right angle with the radial direction of the optical disk (a tangential-direction) can be changed.
In addition, the adjustment screws 119, 120 (placed at the positions of the leaf springs 110, 108) are rotated in the same direction by the same angle to cause the other end of each of the guide shafts 104, 105 opposite to the turntable 102 to be moved in the directions H3xe2x80x2, H1xe2x80x2 (upward direction) or the directions H3xe2x80x3, H1xe2x80x3 (downward direction) in the same orientation by the same distance, resulting in that the entire optical pickup 106 engaged with the guide shafts 104, 105 is inclined, thereby an angle of the optical axis of the objective lens 106a in regard to the radial direction of the optical disk can be changed.
In the prior art, when the optical axis of the objective lens 106a is adjusted by the adjustment screws 119, 120 and 121 in regard to the aforesaid guide shafts 104, 105, it was necessary to align in advance a neutral position of each of the adjustment screws 119, 120, 121 with an initial position of each of the adjustment screws 119, 120, 121, i.e. a position where the axis of each of the guide shafts 104, 105 becomes in parallel with the disk mounting surface 102a of the turntable 102.
In the prior art optical disk device 100, the sheet metal machined by a press machining operation was used due to the fact that the sheet metal could be less-expensive and its rigidity was high, although a method in which the height of each of the adjustment screws 119, 120 and 121 is aligned with the neutral position in reference to the plane of chassis 101 could not attain a machining accuracy of the sheet metal, so that it could not provide an accuracy for the fixing plane of the spindle motor 103 having the turntable 102 shown in FIG. 6 fixed thereto and a degree of parallel state between an axis of each of the guide shafts 104, 105 and the disk mounting surface 102a of the turntable 102 having the optical disk mounted thereon was out of the desired value.
In view of the foregoing, in the prior art, an alignment of neutral position of each of the adjustment screws 119, 120 and 121 was carried out in reference to the disk mounting surface 102a of the turntable 102. As its method, at first, a reflecting plate such as a mirror or the like was mounted on the disk mounting surface 102a, laser beams produced from a laser length measuring unit were struck against the different three points on the reflecting surface to measure a distance and generate a reference plane. Then, the laser beam crossing at a right angle with the aforesaid reference plane was incident on the upper surface of the guide shaft 104 shown in FIG. 6, the other end of the guide shaft 104 was rotated in the direction of the arrow H1 by the adjustment screw 120 while an inclination of the reflected beam was being observed, it was adjusted to cause the reflected beam to be substantially coincided with the incident beam and then the neutral position of the adjustment screw 120 was aligned to attain a degree of parallel between the axis of the guide shaft 104 and the disk mounting surface 102a. Similarly, also as to the guide shaft 105, its height and the height of axis of the guide shaft 104 were aligned to each other, and at the same time the neutral positions of the adjustment screws 119, 121 were aligned to attain a degree of parallel.
However, in the case of the prior art optical disk device 100, when the neutral position of each of the adjustment screws 119, 120 and 121 was aligned to each other, the reference plane with the disk mounting surface 102a of the turntable 102 had to be set by calculation for every one unit of the optical disk device, resulting in that its workability was deteriorated.
In addition, although an optical measuring system using a laser beam to improve an accuracy of measurement was employed to perform the aforesaid measurement of the reference plane and the neutral position alignment of each of the adjustment screws 119, 120 and 121, there occurred a problem that a stage of neutral position alignment not only became complex, but also application of expensive measuring unit caused its facility expenditure to be increased and a cost of the optical disk device per unit was also increased.
It is an object of the present invention to provide an optical disk device in which a neutral position alignment for each of the adjustment screws can be easily carried out and in a high accuracy manner without increasing its cost while its workability is being improved.
As the first solving means for overcoming the aforesaid problem, the present invention is characterized in that a spindle motor on which a turntable having a disk mounting surface for use in mounting an optical disk is rotatably attached, an optical pickup for use in recording or reproducing information onto or from the optical disk, guide shafts for guiding the optical pickup in a radial direction of the optical disk, supporting members for supporting both ends of the guide shafts, and adjustment means having a mounting surface for mounting both ends of the guide shafts and for moving the mounting surface to move at least one end of each of the guide shafts in a direction substantially crossing at a right angle with the surface of a chassis are arranged on the chassis formed by a sheet metal, and the chassis is provided with resin fixing members having a fixing surface to attach and fix the spindle motor and resin reference members having a reference plane in parallel with the fixing surface.
Further, as the second solving means, the reference members are arranged at three locations at outer edge part surrounding the central part of the chassis.
Further, as the third solving means, the fixing members are arranged at three locations in the chassis.
Further, as the fourth solving means, the fixing members and the reference members are molded simultaneously by one molding die.
Further, as the fifth solving means, the fixing members and the reference members are formed at the chassis by an outsert molding.